The dietary treatments and all blood draws will be carried out in the General Clinical Research Center (GCRC) at University of Florida. Previous research from has shown that both metallothionein gene expression and specific zinc transporter genes in blood leukocyte subsets are directly proportional to dietary zinc intake. By using cDNA array analysis and quantitative PCR technology with blood RNA, those genes most sensitive to zinc nutrition will be identified for the purpose of developing zinc status assessment methods on how zinc functions in human biology.